offset question! help please!!!

Hey guys I have a bone stock honda 300 2wd. I’m starting my build off with new wheels and tires. I am ordering a custom wheel and tire setup off pure offroad. I know what tire sizes I want I am just stumped on wheel off set. I am getting 12 inch wheels and when your ordering wheels off that website there is a drop box that says wheel size and bolt pattern and offset and it names a bunch of options then one of the options is "I don’t know". So since I don’t know my offset for my fourwheeler that’s what I chose, beside the "I don’t know" it said sl chose machine below so I picked "honda solid rear axle". So my question is with me just picking that did it get the right offset I need for my fourwheeler? Thanks in advance!!